1. Technological Field
This invention is generally concerned with electronic equipment enclosures adapted to mechanically and electrically interface with plug-in type functional modules. More particularly, embodiments of the invention relate to a card cage system that can be readily customized by a user to accommodate a variety of functional module sizes, types, configurations, and arrangements.
2. Related Technology
Electronic equipment enclosures are used in a number of different industries and applications and generally serve to receive one or more pieces of electronic equipment and devices in such a way that the individual electronic components can operably interact with each other and/or with the electronic equipment enclosure. In some instances, such electronic equipment enclosures are configured to permit the use of one or more “plug-in” functional modules that electrically and mechanically interface with the electronic equipment enclosure and/or with other functional modules.
More specifically, many electronic equipment enclosures include internal structures configured to removably receive one or more functional modules in a desired arrangement. Such internal structures are often referred to as “card cages.” The card cage is configured so that a user can define the functionality of the electronic equipment enclosure by selecting particular functional modules to be employed in the electronic equipment enclosure. In the event that it is desired to modify the functionality of a particular electronic equipment enclosure, such changes can be made simply by positioning additional functional modules in the card cage of the electronic equipment enclosure and/or by removing selected functional modules from the card cage of the electronic equipment enclosure.
The functionality implemented by any particular functional module or group of functional modules can vary widely. Notwithstanding their functional differences however, such functional modules may share a number of similar structural features.
For example, typical functional modules employed in conjunction with card cages include a printed circuit board, or “card,” attached to a front panel that may include various indicators, readouts, and/or connectors. Circuitry disposed on the card communicates with such indicators, readouts and connectors and serves to implement the functionality associated with that particular functional module. Various connectors on the rear of the card permit communication between the functional module and other functional modules or components associated with the electronic equipment enclosure. Additionally, the front panel of the functional module typically includes a number of fasteners that engage corresponding structure of the card cage and thereby aid in removable retention of the functional module within the electronic equipment enclosure.
Conventional card cages for receiving such functional modules typically consist of mounting rails, card guides, and a backplane, and can be oriented horizontally or vertically. A typical horizontal card cage consists of one or more uniformly spaced card slots. Each card slot can accommodate a single uniformly sized functional module. The card slots are oriented horizontally and stacked vertically. Vertically oriented mounting rails are located on the left and right sides at the front of the card cage. A backplane is positioned at the rear of the card cage. The backplane typically consists of a printed circuit board containing connectors for each card slot.
Card guides are positioned on the left and right sides of the card cage and run from the front of the card cage back to the backplane. The card guides contain channels which guide the edges of the functional module PCB during insertion and align the connectors on the functional module with the corresponding backplane connectors. The functional modules are slid between corresponding pairs of card guides and the retention fasteners on the ends of the module front panel engage the mounting rails. A functional module can be taller than a single card slot by incorporating a larger front panel and additional printed circuit boards. The module height generally must be a multiple of the single slot height. However, the width of the module is generally constrained by the distance between the mounting rails of the card cage.
Such card cage arrangements serve to limit, at least, the size of the module, and corresponding card, which can be disposed within a single card cage slot. Thus, the functionality associated with a relatively wider functional module, such as might be required to permit the use of additional circuits and components, can only be implemented by positioning a series of relatively narrow cards above one another. As discussed below however, such arrangements can be problematic.
For example, each separate card must have its own electrical connection with the connectors on the card cage backplane. Moreover, the separate cards may each require additional structure, circuitry, or connections such as cables, for electrical communication with adjacent, or other, cards in the card cage system. Such requirements contribute to relatively high production costs for functional modules having these types of cards, and also serve to complicate installation. Further, in the event a functional module fails to operate properly, the use of a relatively larger number of electrical interfaces and connections impairs troubleshooting, diagnosis, and repair of the functional module.
The foregoing problems are likewise a matter of concern where two functional modules are arranged in an edge-to-edge type of arrangement. Moreover, such edge-to-edge arrangements implicate other problems as well. For example, conventional card cages configured to accommodate two single-wide cards in an edge-to-edge arrangement necessarily include a central structural element that defines a guide rail on either side. The guide rails provide support to an edge of each of the single-wide cards when those cards are received in the card cage. However, the presence of the center guide rails effectively prevents use of a double-wide, or larger, card in the same slot.
In particular, the center guide rails typically extend to the front of the equipment enclosure chassis and thus act to prevent insertion of the double-wide, or larger, card by blocking the path of the card edge. Thus, such configurations materially impair, among other things, the flexibility and the usefulness of conventional electronic equipment enclosures by limiting the ability of the user to change the arrangement of cards used in the electronic equipment enclosure, and by acting as a constraint on the size of the functional modules that may be employed.
Yet another area of concern with respect to typical arrangements of functional modules and card cages relates to the structures and devices typically employed to attach the functional module to the electronic equipment enclosure. In particular, many functional modules include a front panel with a flange that receives one or more screws. positioned to engage the card cage rail and thereby secure the functional module to the card-cage rail. Typically however, this flange is configured and arranged so as to extend laterally beyond the periphery of the card. Thus configured, such modules cannot be positioned edge-to-edge, even if the guide rails of the card cages would otherwise permit such an arrangement, because the flanges and associated screws of the adjacent functional modules would mechanically interfere with each other.
Accordingly, what is needed is a card cage system having features directed to addressing the foregoing exemplary concerns, as well as other concerns not specifically enumerated herein. An exemplary card cage system should permit a user to readily customize the card cage to accommodate a variety of card sizes, types, configurations, and arrangements.